Screening for antibodies against the CARP VIII antigen is used in cases of suspected paraneoplastic cerebral degeneration associated with malignant melanoma.
The presence of autoantibodies against carbonic anhydrase related protein VIII (CARP VIII) has been reported in patients with malignant melanoma-related paraneoplastic degeneration (PCD). Antibodies against the CARP VIII antigen have not been observed in the serum of patients with cerebral degeneration associated with other tumors or with malignant melanoma without paraneoplastic syndromes. Rarely, it can be observed in ovarian cancer.
The CARP VIII antigen is an intracellular protein with a molecular weight of 29 kDa of Purkinje cells. In general, immunotherapy treatment is more effective against autoantibodies directed against extracellular antigens than for autoantibodies against intracellular antigens.